//
// execution/allocator.hpp
// ~~~~~~~~~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2022 Christopher M. Kohlhoff (chris at kohlhoff dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//

#ifndef ASIO_EXECUTION_ALLOCATOR_HPP
#define ASIO_EXECUTION_ALLOCATOR_HPP

#if defined(_MSC_VER) && (_MSC_VER >= 1200)
# pragma once
#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)

#include "asio/detail/config.hpp"
#include "asio/detail/type_traits.hpp"
#include "asio/execution/executor.hpp"
#include "asio/execution/scheduler.hpp"
#include "asio/execution/sender.hpp"
#include "asio/is_applicable_property.hpp"
#include "asio/traits/query_static_constexpr_member.hpp"
#include "asio/traits/static_query.hpp"

#include "asio/detail/push_options.hpp"

namespace asio {

#if defined(GENERATING_DOCUMENTATION)

    namespace execution {

    /// A property to describe which allocator an executor will use to allocate the
    /// memory required to store a submitted function object.
    template <typename ProtoAllocator>
    struct allocator_t
    {
      /// The allocator_t property applies to executors, senders, and schedulers.
      template <typename T>
      static constexpr bool is_applicable_property_v =
        is_executor_v<T> || is_sender_v<T> || is_scheduler_v<T>;

      /// The allocator_t property can be required.
      static constexpr bool is_requirable = true;

      /// The allocator_t property can be preferred.
      static constexpr bool is_preferable = true;

      /// Default constructor.
      constexpr allocator_t();

      /// Obtain the allocator stored in the allocator_t property object.
      /**
       * Present only if @c ProtoAllocator is non-void.
       */
      constexpr ProtoAllocator value() const;

      /// Create an allocator_t object with a different allocator.
      /**
       * Present only if @c ProtoAllocator is void.
       */
      template <typename OtherAllocator>
      allocator_t<OtherAllocator operator()(const OtherAllocator& a);
    };

    /// A special value used for accessing the allocator_t property.
    constexpr allocator_t<void> allocator;

    } // namespace execution

#else // defined(GENERATING_DOCUMENTATION)

    namespace execution {

        template<typename ProtoAllocator>
        struct allocator_t {
#if defined(ASIO_HAS_VARIABLE_TEMPLATES)
            template <typename T>
            ASIO_STATIC_CONSTEXPR(bool,
              is_applicable_property_v = (
                is_executor<T>::value
                  || conditional<
                      is_executor<T>::value,
                      false_type,
                      is_sender<T>
                    >::type::value
                  || conditional<
                      is_executor<T>::value,
                      false_type,
                      is_scheduler<T>
                    >::type::value));
#endif // defined(ASIO_HAS_VARIABLE_TEMPLATES)

            ASIO_STATIC_CONSTEXPR(bool, is_requirable = true);

            ASIO_STATIC_CONSTEXPR(bool, is_preferable = true);

            template<typename T>
            struct static_proxy {
#if defined(ASIO_HAS_DEDUCED_QUERY_STATIC_CONSTEXPR_MEMBER_TRAIT)
                struct type
                {
                  template <typename P>
                  static constexpr auto query(ASIO_MOVE_ARG(P) p)
                    noexcept(
                      noexcept(
                        conditional<true, T, P>::type::query(ASIO_MOVE_CAST(P)(p))
                      )
                    )
                    -> decltype(
                      conditional<true, T, P>::type::query(ASIO_MOVE_CAST(P)(p))
                    )
                  {
                    return T::query(ASIO_MOVE_CAST(P)(p));
                  }
                };
#else // defined(ASIO_HAS_DEDUCED_QUERY_STATIC_CONSTEXPR_MEMBER_TRAIT)
                typedef T type;
#endif // defined(ASIO_HAS_DEDUCED_QUERY_STATIC_CONSTEXPR_MEMBER_TRAIT)
            };

            template<typename T>
            struct query_static_constexpr_member :
                    traits::query_static_constexpr_member<
                            typename static_proxy<T>::type, allocator_t> {
            };

#if defined(ASIO_HAS_DEDUCED_STATIC_QUERY_TRAIT) \
 && defined(ASIO_HAS_SFINAE_VARIABLE_TEMPLATES)
            template <typename T>
            static ASIO_CONSTEXPR
            typename query_static_constexpr_member<T>::result_type
            static_query()
              ASIO_NOEXCEPT_IF((
                query_static_constexpr_member<T>::is_noexcept))
            {
              return query_static_constexpr_member<T>::value();
            }

            template <typename E, typename T = decltype(allocator_t::static_query<E>())>
            static ASIO_CONSTEXPR const T static_query_v
              = allocator_t::static_query<E>();
#endif // defined(ASIO_HAS_DEDUCED_STATIC_QUERY_TRAIT)
            //   && defined(ASIO_HAS_SFINAE_VARIABLE_TEMPLATES)

            ASIO_CONSTEXPR ProtoAllocator

            value() const {
                return a_;
            }

        private:
            friend struct allocator_t<void>;

            explicit ASIO_CONSTEXPR allocator_t(const ProtoAllocator &a)
                    : a_(a) {
            }

            ProtoAllocator a_;
        };

#if defined(ASIO_HAS_DEDUCED_STATIC_QUERY_TRAIT) \
 && defined(ASIO_HAS_SFINAE_VARIABLE_TEMPLATES)
        template <typename ProtoAllocator> template <typename E, typename T>
        const T allocator_t<ProtoAllocator>::static_query_v;
#endif // defined(ASIO_HAS_DEDUCED_STATIC_QUERY_TRAIT)
        //   && defined(ASIO_HAS_SFINAE_VARIABLE_TEMPLATES)

        template<>
        struct allocator_t<void> {
#if defined(ASIO_HAS_VARIABLE_TEMPLATES)
            template <typename T>
            ASIO_STATIC_CONSTEXPR(bool,
              is_applicable_property_v = (
                is_executor<T>::value
                  || conditional<
                      is_executor<T>::value,
                      false_type,
                      is_sender<T>
                    >::type::value
                  || conditional<
                      is_executor<T>::value,
                      false_type,
                      is_scheduler<T>
                    >::type::value));
#endif // defined(ASIO_HAS_VARIABLE_TEMPLATES)

            ASIO_STATIC_CONSTEXPR(bool, is_requirable = true);

            ASIO_STATIC_CONSTEXPR(bool, is_preferable = true);

            ASIO_CONSTEXPR allocator_t() {
            }

            template<typename T>
            struct static_proxy {
#if defined(ASIO_HAS_DEDUCED_QUERY_STATIC_CONSTEXPR_MEMBER_TRAIT)
                struct type
                {
                  template <typename P>
                  static constexpr auto query(ASIO_MOVE_ARG(P) p)
                    noexcept(
                      noexcept(
                        conditional<true, T, P>::type::query(ASIO_MOVE_CAST(P)(p))
                      )
                    )
                    -> decltype(
                      conditional<true, T, P>::type::query(ASIO_MOVE_CAST(P)(p))
                    )
                  {
                    return T::query(ASIO_MOVE_CAST(P)(p));
                  }
                };
#else // defined(ASIO_HAS_DEDUCED_QUERY_STATIC_CONSTEXPR_MEMBER_TRAIT)
                typedef T type;
#endif // defined(ASIO_HAS_DEDUCED_QUERY_STATIC_CONSTEXPR_MEMBER_TRAIT)
            };

            template<typename T>
            struct query_static_constexpr_member :
                    traits::query_static_constexpr_member<
                            typename static_proxy<T>::type, allocator_t> {
            };

#if defined(ASIO_HAS_DEDUCED_STATIC_QUERY_TRAIT) \
 && defined(ASIO_HAS_SFINAE_VARIABLE_TEMPLATES)
            template <typename T>
            static ASIO_CONSTEXPR
            typename query_static_constexpr_member<T>::result_type
            static_query()
              ASIO_NOEXCEPT_IF((
                query_static_constexpr_member<T>::is_noexcept))
            {
              return query_static_constexpr_member<T>::value();
            }

            template <typename E, typename T = decltype(allocator_t::static_query<E>())>
            static ASIO_CONSTEXPR const T static_query_v
              = allocator_t::static_query<E>();
#endif // defined(ASIO_HAS_DEDUCED_STATIC_QUERY_TRAIT)
            //   && defined(ASIO_HAS_SFINAE_VARIABLE_TEMPLATES)

            template<typename OtherProtoAllocator>
            ASIO_CONSTEXPR allocator_t<OtherProtoAllocator>

            operator()(
                    const OtherProtoAllocator &a) const {
                return allocator_t < OtherProtoAllocator > (a);
            }
        };

#if defined(ASIO_HAS_DEDUCED_STATIC_QUERY_TRAIT) \
 && defined(ASIO_HAS_SFINAE_VARIABLE_TEMPLATES)
        template <typename E, typename T>
        const T allocator_t<void>::static_query_v;
#endif // defined(ASIO_HAS_DEDUCED_STATIC_QUERY_TRAIT)
        //   && defined(ASIO_HAS_SFINAE_VARIABLE_TEMPLATES)

#if defined(ASIO_HAS_CONSTEXPR) || defined(GENERATING_DOCUMENTATION)
        constexpr allocator_t<void> allocator;
#else // defined(ASIO_HAS_CONSTEXPR) || defined(GENERATING_DOCUMENTATION)
        template<typename T>
        struct allocator_instance {
            static allocator_t<T> instance;
        };

        template<typename T>
        allocator_t<T> allocator_instance<T>::instance;

        namespace {
            static const allocator_t<void> &allocator = allocator_instance<void>::instance;
        } // namespace
#endif

    } // namespace execution

#if !defined(ASIO_HAS_VARIABLE_TEMPLATES)

    template<typename T, typename ProtoAllocator>
    struct is_applicable_property<T, execution::allocator_t<ProtoAllocator> >
            : integral_constant<bool,
                    execution::is_executor<T>::value
                    || conditional<
                            execution::is_executor<T>::value,
                            false_type,
                            execution::is_sender<T>
                    >::type::value
                    || conditional<
                            execution::is_executor<T>::value,
                            false_type,
                            execution::is_scheduler<T>
                    >::type::value> {
    };

#endif // !defined(ASIO_HAS_VARIABLE_TEMPLATES)

    namespace traits {

#if !defined(ASIO_HAS_DEDUCED_STATIC_QUERY_TRAIT) \
 || !defined(ASIO_HAS_SFINAE_VARIABLE_TEMPLATES)

        template<typename T, typename ProtoAllocator>
        struct static_query<T, execution::allocator_t<ProtoAllocator>,
                typename enable_if<
                        execution::allocator_t<ProtoAllocator>::template
                        query_static_constexpr_member<T>::is_valid
                >::type> {
            ASIO_STATIC_CONSTEXPR(bool, is_valid = true);

            ASIO_STATIC_CONSTEXPR(bool, is_noexcept = true);

            typedef typename execution::allocator_t<ProtoAllocator>::template
            query_static_constexpr_member<T>::result_type result_type;

            static ASIO_CONSTEXPR result_type

            value() {
                return execution::allocator_t<ProtoAllocator>::template
                query_static_constexpr_member<T>::value();
            }
        };

#endif // !defined(ASIO_HAS_DEDUCED_STATIC_QUERY_TRAIT)
        //   || !defined(ASIO_HAS_SFINAE_VARIABLE_TEMPLATES)

    } // namespace traits

#endif // defined(GENERATING_DOCUMENTATION)

} // namespace asio

#include "asio/detail/pop_options.hpp"

#endif // ASIO_EXECUTION_ALLOCATOR_HPP
